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Level Crossing Interface Railway Interface Unit Design

Level Crossing Interface – Railway Interface Unit Design

Roads and Traffic Authority

www.nsw.rta.gov.au

Title: Level Crossing Interface – Railway Interface Unit Design

Document no: LX-SP-001

Version: 1

Date: 21-Dec-2009

Approved by: P. Margison

Copyright © 2009 Roads and Traffic Authority of NSW

This work is protected by copyright. Apart from any fair use as permitted under the Copyright Act 1968, no part may be reproduced in any way without prior written consent from the Roads and Traffic Authority of NSW.

Disclaimer and Conditions For Use This Specification has been prepared by the Roads and Traffic Authority of New South Wales (referred to herein as RTA) for use, insofar as it is applicable, in the State of New South Wales for equipment supplied under an RTA procurement order or contract, or under a procurement order or contract from another party that is required in writing by the RTA to use this Specification.

The use of this RTA Specification other than by those parties stated above and in the manner stated above is not recommended by the RTA. Any such use is entirely the decision of the user alone. The RTA disclaims all responsibilities arising whether directly or indirectly from any such use. The RTA does not warrant that this Specification is error free, nor does RTA warrant the suitability, fitness or otherwise of this Specification for any stated or implied purposes expressed or implied in this Specification or other documents. By using this Specification, the user agrees to indemnify the RTA against the full amount of all expenses, losses, damages and costs (on a full indemnity basis and whether or not incurred by or awarded against the RTA) which may be suffered by any person or the RTA in connection with or arising out of the use of this Specification in any manner.

The RTA is not under any duty to inform you of any errors in or changes to the Specification.

Revision history

Version Date Details

0a 23-Jul-2008 Initial draft

0b 23-Jan-2009 Updated and edited significantly following initial scrutiny.

0c 24-Apr-2009 Updated following review by D. Quail. Comments documented in LX-RR-003.

0d 10-Sep-2009 Updated following review by F.Johnson, G.Malepa, R.O'keefe, P.Yu, J.Tough, A.Dixon, L.Clay, K.Ironside, B.Taylor, N.Rubbi, G.Farrelly, D. Quail. Comments documented in LX-RR-003.

Roads and Traffic Authority of New South Wales Traffic Management Branch PO Box 1927 Strawberry Hills NSW 2012 Australia

Telephone: +61 2 8396 1602 Facsimile: +61 2 8396 1600

of 29 Uncontrolled when printed LX-SP-001, Version 1

http://www.nsw.rta.gov.au/


Contents

1 Introduction................................................................................................ 5 1.1 Purpose..............................................................................................................5 1.2 Scope..................................................................................................................5 1.3 Definitions and abbreviations..........................................................................5 1.4 References .........................................................................................................6

2 General Description................................................................................... 7 2.1 Train Demand...................................................................................................7 2.2 Level Crossing Operating ................................................................................7 2.3 Traffic Light Response .....................................................................................8 2.4 Traffic Light Response Feedback....................................................................8

3 Railway Interface Unit Circuit Diagram.................................................. 9

4 Explanation ...............................................................................................11 4.1 Connections to the Railway Signalling System ...........................................11 4.2 Connections to the Traffic Signal Controller..............................................11 4.3 Signals and Indications ...................................................................................11 4.4 Components....................................................................................................12

5 Fault Identification at Site.......................................................................15 5.1 LED Indications...............................................................................................15 5.2 Traffic Signal Controller Detection..............................................................16

Appendix A FMEA ......................................................................................19

LX-SP-001, Version 1 Uncontrolled when printed of 29


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1 Introduction

1.1 Purpose The purpose of this document is to define how railway interface unit (RIU) operates. The RIU can be used to interface to level crossings operated by any rail authority involved (RailCorp, ARTC, RIC, etc).

1.2 Scope This document covers all aspects of the railway interface unit hardware. There is no software on the railway interface unit.

Within this document it is assumed that there are no other inputs or outputs being used. Ie, this document assumes usage of external detector inputs 1 to 7 and non signal group outputs 1 to 3. In practice at a specific intersection these may be used for other purposes and the actual identification numbers of the external detector inputs and non signal group outputs used for the RIU may differ.

It does not cover the operating principles or design considerations of the railway-road interface. This information can be found in Level Crossing Interface – Concept of Operations, [2] and Level Crossing Interface – Traffic Signal Design Guidelines, [3].

The installation and testing of the RIU in a traffic signal controller and connection to the railway level crossing can be found in Level Crossing Interface – Installation and Testing [4].

1.3 Definitions and abbreviations Term Meaning

ARTC Australian Rail Track Corporation

RailCorp Rail Corporation New South Wales

RIC Rail Infrastructure Corporation

RIU Railway Interface Unit

RTA Roads and Traffic Authority of NSW

TD Train Demand – an indication from the level crossing to the traffic signal controller indicating a train is approaching. (This signal ends when the train has cleared the crossing.) It is inferred from the TDNC and TDNO signals.

TDNC The half of the train demand signal which is normally closed when there is no train demand.

TDNO The half of the train demand signal which is normally open when there is no train demand.

TDRT Train Demand Response Time – the advance warning time required by the traffic signal controller of an approaching train prior to the level crossing commencing to operate.

TLR Traffic Light Response – indication from the traffic signal controller to the level crossing indicating that the traffic signal controller is ready for the level crossing to commence operating. (This signal remains active while the Train Demand signal is present.)

TLRFB Traffic Light Response Feedback – an indication from the level crossing to the traffic signal controller confirming that the level crossing has received the Traffic Light Response indication.



Term Meaning

TLRH Traffic Light Response High relay

TLRL Traffic Light Response Low relay

TMB Traffic Management Branch

TSC Traffic Signal Controller

TSC/4 Controller A TSC that complies with the Control Equipment for Road Traffic Signals specification [6].

XE Crossing Operating – indication from the level crossing to the traffic signal controller indicating the level crossing flashing lights are operating. It is inferred from the XENC and XENO signals.

XENC The half of the crossing operating signal which is normally closed when the crossing is not operating.

XENO The half of the crossing operating signal which is normally open when the crossing is operating.

1.4 References [1] RailCorp – Roads & Traffic Authority, Level Crossing – Traffic Light Design Interface Agreement,

30 May 2008

[2] LX-CO-001, Level Crossing Interface – Concept of Operations

[3] LX-DG-001, Level Crossing Interface – Design Guidelines

[4] LX-IP-001, Level Crossing Interface – Railway Interface Unit Installation and Testing

[5] Traffic Signal Design, Section 15 – Special Situations

[6] Equipment Specification No. TSC/4, Control Equipment for Road Traffic Signals, December 1999



2 General Description A description of the operating principles of the interface between the railway signalling system and the traffic signal controller is given in Level Crossing Interface – Concept of Operations, [2].

The railway interface unit (RIU) consists of two distinct parts. The first part conveys indications from the rail authority system to the RTA traffic signal controller and the second part of the RIU provides an indication from the RTA traffic signal controller to the railway signalling system.

2.1 Train Demand Train demand is derived from the state of the TDR relay in the railway signalling system. This relay is normally energised, and releases when the train is detected. There are two voltage free circuits comprising the contacts of the TDR relay:

Train Demand Normally Closed circuit. This contact is normally closed and opens when the train is detected.

Train Demand Normally Open circuit. This contact is normally open and closes when the train is detected.

TDNC relay (RL4) monitors the state of the normally closed contact of the railway signalling system TDR relay. The TDNC relay is energised when there is no train demand.

TDNO relay (RL3) monitors the state of the normally open contacts of the same railway signalling system TDR relay. The TDNO relay is not energised when there is no train demand.

By monitoring both contacts the interface board and traffic signal controller have a double check on the condition of the railway signalling system TD relay contacts, so that if these contacts are not in the reverse state of each other under steady conditions, then the traffic signal controller has an indication of a failure of the train detection circuitry. In addition, the double contacts provide monitoring of the interface cable, the relays on the RIU, the contacts of the relays on the RIU and the traffic signal controller inputs.

2.2 Level Crossing Operating Crossing operating is derived from the state of the two relays CSER and SSER in the railway signalling system. Both relays are normally energised and if either (or both) is released, the level crossing is operating. There are two voltage free circuits comprising contacts of the CSER and SSER relays:

Crossing operating normally closed circuit. This circuit is normally closed and opens when the level crossing is operating.

Crossing operating normally open circuit. This circuit is normally open and closes when the level crossing is operating.

XENC relay (RL2) monitors the state of the normally closed circuit of the level crossing warning lights. The XENC relay is energised when the level crossing warning lights are inactive.

XENO relay (RL1) monitors the state of the normally open circuit of the level crossing warning lights. The XENO relay is not energised when the level crossing warning lights are inactive.

By monitoring both contacts the interface board and traffic signal controller have a double check on the condition of the railway signalling system relay contacts, so that if these contacts are not in the reverse state of each other under steady conditions, then the traffic signal controller has an indication of a failure of the crossing operating circuitry.




2.3 Traffic Light Response When the traffic signal controller has the intersection signals in a condition where it is safe for the level crossing warning light to start flashing it provides a Traffic Light Response (TLR) indication. TLR is a normally open circuit which is closed to provide the indication.

The output facilities provided by a traffic signal controller differ dependent on the manufacturer and the type of traffic signal controller. In general, two methods are employed:

use of special facility outputs; and

use of WAIT outputs.

These two methods are explained in the following sub-sections.

2.3.1 Special Facility Outputs

The TLR circuit is closed by energising the TLRL and TLRH relays (RL5 and RL6) using the special facility outputs (OUT 1 and OUT 3) of the traffic signal controller.

TLRL and TLRH provide a double cut circuit which completes the rail authority circuits and provides the redundancy required by railway signalling systems. These relays are powered from the traffic signal controller special facility output supply and are switched, as mentioned above, by the active low operation of the special facility outputs. TLRL is energised by the first traffic signal controller special facility output while TLRH is energised by the third special facility output.

The traffic signal controller monitors the TLR feedback signal. If the traffic signal controller observes a TLR feedback indication when TLR is not intended to be given (due to software or hardware fault) it can prevent TLRH from operating. TLRH is prevented from operating, and hence prevent the TLR indication being provided to the railway signalling system, by an active low operation of the second special facility output (OUT 2). The second special facility output (OUT 2) also protects against a traffic signal controller logic module hardware failure that puts all outputs low.

2.3.2 Wait Outputs

When the traffic signal controller has the intersection signals in a condition where it is safe for the level crossing warning light to start flashing it provides a Traffic Light Response (TLR) indication. TLR is a normally open circuit which is closed to provide the indication. It is closed by energising the TLRL and TLRH relays (RL5 and RL6) using the “WAIT” outputs (COUT 1 and COUT 3) of the traffic signal controller.

TLRL and TLRH provide a double cut circuit which completes the rail authority circuits and provides the redundancy required by railway signalling systems. These relays are powered from the traffic signal controller “WAIT” supply voltage and are switched, as mentioned above, by the active low operation of the “WAIT” outputs. TLRL is energised by the first traffic signal controller “WAIT” output while TLRH is energised by the third “WAIT” output.

The traffic signal controller monitors the TLR feedback signal. If the traffic signal controller observes a TLR feedback indication when TLR is not intended to be given (due to software or hardware fault) it can prevent TLRH from operating. TLRH is prevented from operating, and hence prevent the TLR indication being provided to the railway signalling system, by an active low operation of the second “WAIT” output (COUT 2). The second “WAIT” output (COUT 2) also protects against a traffic signal controller logic module hardware failure that puts all outputs low.

2.4 Traffic Light Response Feedback The TLRFB relay (RL7) monitors a contact in the rail authority system, which confirms, (for the interface and traffic signal controller), that the rail authority system has received the Traffic Light Response (TLR) from the RTA traffic signal controller.


3 Railway Interface Unit Circuit Diagram




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4 Explanation This section describes:

the connections between the RIU and the railway signalling system;

the connections between the RIU and the traffic signal controller;

the electrical signals and indications on the RIU, including the states the indications can take;

the design principles of the RIU.

4.1 Connections to the Railway Signalling System The RIU provides for eight circuit connections to the railway signalling system providing four indications. These connections generally provide the following indications:

Train demand, TD (Two circuits - one normally open TDNO and one normally closed TDNC when there is no train demand. Normally both circuits change state when a train demand is present, however change in state of either circuit is treated as a valid train demand. A fault is registered if only one circuit changes state.)

Crossing operating, XE (Two circuits - one normally open and one normally closed circuit when the crossing is not operating. Normally both circuits change state when the crossing is operating, however change in state of either circuit is treated as the crossing is operating. A fault is registered if only one circuit changes state.)

Signalling circuits used for traffic light response, TLR (normally open, closed when the traffic signal controller is ready for the crossing to operate)

Traffic light response feedback, TLRF (normally open, closed when the rail authority has received the TLR signal)

Nominal 12v DC power supply (provided by the rail authority)

Spare

4.2 Connections to the Traffic Signal Controller The RIU provides for the following connections to the Traffic Signal Controller:

32v AC detector power supply from the TSC for detecting TD, XE and TLRF indications

Nominal 12v DC power supply from the TSC for TD, XE and TRLF circuits

12v DC or 24v DC power supply from the TSC for providing TLR indications1

5 outputs to the TSC providing TD, XE and TLRF indications

Detector return to the TSC

3 inputs from the TSC to drive the TLRL and TLRH relays for providing TLR indications

4.3 Signals and Indications The following section provides a simple description of each LED’s function when the RIU has been correctly installed and the traffic signal controller has been installed and commissioned on site.

LED Status Indication

30v AC Grn (D12) → Lit Power is present

1 TSC/4 controllers are provided with +24v supply, earlier controllers have +12v wait supply.



LED Status Indication

→ Unlit Power is not present

→ Lit Train Demand is present, either or both TDNO or TDNC has changed state

TD Grn (D10)

→ Unlit Train Demand is not present, TDNO is open and TDNC is closed

→ Lit TDNC and TDNO are not in agreement TD Fault Red (D9)

→ Unlit TDNC and TDNO are not in agreement

→ Lit Level crossing is operating, either or both XENO or XENC has changed state

XE Grn (D6)

→ Unlit Level crossing is not operating, XENO is closed and XENC is open

→ Lit XENC and XENO are not in agreement XE Fault Red (D5)

→ Unlit XENC and XENO are in agreement

→ Lit Power is present Relay Supply (D1)

→ Unlit Power is not present

→ Lit TLR is being received by railway signalling system TLRFB Gn (D3))

→ Unlit TLR is not being received by railway signalling system

4.4 Components The following section describes the components of the RIU and their purpose.

Component Function

Relay 1 Provides isolation and indication of XENO from rail authority to TSC inputs

Relay 2 Provides isolation and indication of XENC from rail authority to TSC inputs

Relay 3 Provides isolation and indication of TDNO from rail authority to TSC inputs

Relay 4 Provides isolation and indication of TDNC from rail authority to TSC inputs

Relay 5 Provides isolation and indication of TLR from TSC output to rail authority, must work in conjunction with relay 6 otherwise indication is not provided

Relay 6 Provides isolation and indication of TLR from TSC output to rail authority, must work in conjunction with relay 5 otherwise indication is not provided

Relay 7 Provides isolation and indication of TLRF from rail authority to TSC inputs

Diode 1 Provides green LED indication ‘Relay supply’ of 12v DC to rail authority indication circuits

Diode 2 Provides path to dissipate the energy from the collapsing magnetic field for relay TLRF de-energising to prevent reverse breakdown of ‘TLRFB’ LED

Diode 3 Provides green LED indication ‘TLRFB’ of TLRF circuit being active

Diode 4 Provides path for 32v AC negative half cycle around ‘XE Fault’ LED to prevent reverse breakdown of ‘XE fault’ LED

Diode 5 Provides red LED indication ‘XE fault’

Diode 6 Provides green LED indication ‘XE’ – crossing is operating

Diode 7 Provides path for 32v AC negative half cycle around ‘XE’ LED to prevent reverse breakdown of ‘XE’ LED



Component Function

Diode 8 Provides path for 32v AC negative half cycle around ‘TD Fault’ LED to prevent reverse breakdown of ‘TD fault’ LED

Diode 9 Provides red LED indication ‘TD fault’

Diode 10 Provides green LED indication ‘TD’ – there is a train demand

Diode 11 Provides path for 32v AC negative half cycle around ‘TD’ LED to prevent reverse breakdown of ‘TD’ LED

Diode 12 Provides green LED indication ‘30v AC’ of 32v AC to rail authority indication circuits

Diode 13 Provides alternative path to dissipate the energy from the collapsing magnetic field for relays 1, 2, 3, 4 or 7 de-energising to prevent reverse breakdown of ‘Relay supply’ LED

Diode 14 Ensures that relay 6 can only be operated if COUT3 is low

Diode 15 Provides path to dissipate the energy from the collapsing magnetic field for relay 5 de-energising

Diode 16 Provides path to dissipate the energy from the collapsing magnetic field for relay 6 de-energising

Diode 17 Provides path for 32v AC negative half cycle around ‘30v AC’ LED

Resistor 1 Provides path to dissipate the energy from the collapsing magnetic field for Relay 1 de-energising, and ensures wetting current at the rail authority’s contacts is within an acceptable band




Resistor 5 Regulates current drawn by LED diode 1

Resistor 6 Provides path for to dissipate the energy from the collapsing magnetic field Relay 7 de-energising, and ensures wetting current at the rail authority’s contacts is within an acceptable band, and regulates current drawn by LED diode 3






Resistor 13 Provides load to reduce voltage across relay 5 when 24v supply is used

Resistor 14 Provides load to ensure voltage is dropped across it and none across relay 6 when COUT2 is switched to active low (with 12 v supply used)

Resistor 15 Provides load to reduce voltage across relay 6 when 24v supply is used, and ensures voltage is dropped across it and none across relay 6 when COUT2 is switched to active low



Component Function

Resistor 16 Limits current inrush through relay 5 contacts 9 and 13 caused by interface cable capacitance

Resistor 17 Limits current inrush through relay 6 contacts 9 and 13 caused by interface cable capacitance

LC Unit Capacitor and resistor pair to absorb any back emf generated by the Rail Authority’s TLR relay coil



5 Fault Identification at Site The information provided in this section assumes that the traffic signal controller is on and working correctly.

Repairs to the RIU should not be attempted on site. The technician should only establish that there is a fault with the RIU and not the connections or external signals.

5.1 LED Indications The following tables provide combinations of LED indications, their interpreted meaning and possible causes.

LED Status Possible causes

Relay Supply (D1) → Unlit 12v DC power supply not connected 12v DC power supply failure D1 LED failure Resistor R5 failure (open circuit)

30v AC (D12) → Unlit 32v AC power supply not connected 32v AC power supply failure D12 LED failure Resistor R11 failure (open circuit)

TLRF (D3) → Unlit TLR is not used at the site.

Where used: There is no TLR indication to the railway signalling system There is no TLRF indication from the railway signalling system D3 LED failure Resistor R6 failure (open circuit)

LED Possible causes

TD (D10) and TD Fault (D9) are both lit (with no train demand)

Relay 3 is in its energised state because: relay 3 has failed in this state; or the relay is kept energised by an incorrect TDNO signal from the Rail Authority; or short in interface cable; or there is an electrical short on RIU.

Relay 3, contact 9 failed to break or contact 11 failed to make.

Relay 4 in its energised state because: relay 4 has failed in this state; or the relay is kept energised by an incorrect TDNC signal from the Rail Authority; or short in interface cable; or there is an electrical short on RIU.


The appearance of a Train Demand would cause the TD Fault LED to go off.



LED Possible causes

TD (D10) and TD Fault (D9) are both lit (with a train demand)

Relay 4 in its de-energised state because: relay 4 has failed in this state; or the TDNC signal has not been given by the Rail Authority; or open circuit in interface cable; or there is an electrical open circuit on RIU.


Relay 3 in its de-energised state because: relay 3 has failed in this state; or the TDNO signal has not been given by the Rail Authority; or open circuit in interface cable; or there is an electrical open circuit on RIU.


The removal of the Train Demand would cause the TD Fault LED to go off.

XE and XE Fault are both lit (with no crossing operating)

Relay 1 is in its energised state because: relay 1 has failed in this state; or the relay is kept energised by an incorrect XENO signal from the Rail Authority; or short in interface cable; or there is an electrical short on RIU.


Relay 2 in its energised state because: relay 2 has failed in this state; or the relay is kept energised by an incorrect XENC signal from the Rail Authority; or short in interface cable; or there is an electrical short on RIU.


The appearance of a Crossing Operating indication would cause the XE Fault LED to go off.

XE and XE Fault are both lit (with a crossing operating)

Relay 2 in its de-energised state because: relay 2 has failed in this state; or the XENC signal has not been given by the Rail Authority; or open circuit in interface cable; or there is an electrical open circuit on RIU.


Relay 1 in its de-energised state because: relay 1 has failed in this state; or the XENO signal has not been given by the Rail Authority; or open circuit in interface cable; or there is an electrical open circuit on RIU.


The removal of a Crossing Operating indication would cause the XE Fault LED to go off.

5.2 Traffic Signal Controller Detection The following table provides fault states that can be detected by the traffic signal controller if the correct coding of the Personality has been considered, Level Crossing Interface – Design Guidelines [3].



A technician will need a hand held terminal to observe the state of the signals described below, access to the traffic signal controller information sheet to establish the signals and which detector or WAIT/special facility output it is mapped to.

Fault states Possible causes

TDNC1 & TDNO1 are both closed (with no train demand)

Relay 3 is in its energised state because: relay 3 has failed in this state; or the relay is kept energised by an incorrect TDNO signal from the Rail Authority; or short in interface cable; or there is an electrical short on RIU.


TDNC1 & TDNO1 are both closed (with a train demand)

Relay 4 in its energised state because: relay 4 has failed in this state; or the relay is kept energised by an incorrect TDNC signal from the Rail Authority; or short in interface cable; or there is an electrical short on RIU.


TDNC1 & TDNO1 are both open (with a train demand)

Relay 3 in its de-energised state because: relay 3 has failed in this state; or the TDNO signal has not been given by the Rail Authority; or open circuit in interface cable; or there is an electrical open circuit on RIU.


TDNC1 & TDNO1 are both open (with no train demand)

Relay 4 in its de-energised state because: relay 4 has failed in this state; or the TDNC signal has not been given by the Rail Authority; or open circuit in interface cable; or there is an electrical open circuit on RIU.


XENC1 & XENO1 are both closed (with no train demand)

Relay 1 is in its energised state because: relay 1 has failed in this state; or the relay is kept energised by an incorrect XENO signal from the Rail Authority; or short in interface cable; or there is an electrical short on RIU.


XENC1 & XENO1 are both closed (with a train demand)

Relay 2 in its energised state because: relay 2 has failed in this state; or the relay is kept energised by an incorrect XENC signal from the Rail Authority; or short in interface cable; or there is an electrical short on RIU.


XENC1 & XENO1 are both open (with a train demand)

Relay 1 in its de-energised state because: relay 1 has failed in this state; or the XENO signal has not been given by the Rail Authority; or open circuit in interface cable; or there is an electrical open circuit on RIU.





Fault states Possible causes

XENC1 & XENO1 are both open (with no train demand)

Relay 2 in its de-energised state because: relay 2 has failed in this state; or the XENC signal has not been given by the Rail Authority; or open circuit in interface cable; or there is an electrical open circuit on RIU.


TLRF1 closed with no TLR indication

Relay 5, contacts 8 & 9 failed to break and Relay 4, contacts 8 & 9 failed to break.

Relay 5 and Relay 4 both energised incorrectly due to COUT1 and COUT3 both shorted to earth.

Short in interface cable.

TLRF1 open with TLR indication

Capacitor C1 failed (short circuit) Diode 14 failed (open circuit) Diode 15 failed (reverse breakdown) Diode 16 failed (reverse breakdown) Resistor 6 failed (short circuit) Resistor 13 failed (open circuit) – 24v DC supply Resistor 14 failed (open circuit) – 12v DC supply Resistor 15 failed (open circuit) – 24v DC supply Resistor 16 failed (open circuit) Resistor 17 failed (open circuit) Relay 5 failed:

to energise contact 6 failed to break or contact 8 failed to make contact 11 failed to break or contact 13 failed to make

Relay 6 failed: to energise contact 6 failed to break or contact 8 failed to make contact 11 failed to break or contact 9 failed to make

Rail Authority has not provided TLR Feedback indication Relay 7 failed:

to energise contact 11 failed to break or contact 9 failed to make

Open circuit in interface cable. Open circuit on RIU.


Appendix A FMEA In the following where reference is made to WAIT outputs, these also cover special facility outputs where used.

No. Item Component Failure Mode Local Effects Next Level External Effects External Influences Detection Method Notes Assumption

1 R1 Relay - XENO Contact 6 welded Fails to switch over when XE applied

XENO1 latching does not register in TSC

TSC reverts to normal operation when TD removed. TSC will log a fault with the XE indication as XENO and XENC do not correspond. As long as XENC operates, on next TD applied TSC will "see" TD and XE go "on" together and react appropriately.

Crossing operating present

By TSC seeing XENO1 low when XENC1 is low.

Possibly caused by R8 or R9 shorting

Relay contacts are not Forced-guided contacts, ie one can change while the other does not.

1.1 Contact 8 welded Fails to switch over when XE removed



NO Crossing operating present

By TSC seeing XENO1 high when XENC1 is high





None NO Crossing operating present

By technician observing 'XE fault' LED lit and 'XE' LED lit



1.3 Contact 11 welded Fails to switch over when XE applied


None Crossing operating present




1.4 Unable to energise - Contacts 6 & 11 effectively welded

Fails to switch over when XE applied

XENO1 and XENO2 latching does not register in TSC



By TSC seeing XENO1 low when XENC1 is low By technician observing 'XE fault' LED lit and 'XE' LED lit

Relay coil open cct. XENO indication - open cct.


1.5 Unable to de-energise - Contacts 8 & 9 effectively welded

Fails to switch over when XE removed

XENO1 and XENO2 latching does not register in TSC



By TSC seeing XENO1 high when XENC1 is high By technician observing 'XE fault' LED lit and 'XE' LED lit

Excessive current welds contacts. XENO continuously applied.


2 R2 Relay - XENC Contact 6 welded Fails to switch over when XE removed

XENC2 latching does not register in TSC

None NO Crossing operating present






None Crossing operating present






TSC assumes there is a XE present, but will a log a fault as XENC does not match.


By TSC seeing XENC1 high when XENO1 is high







By TSC seeing XENC1 low when XENO1 is low




Fails to switch over when XE removed

XENC1 and XENC2 latching does not register in TSC



By TSC seeing XENC1 low when XENO1 is low By technician observing 'XE fault' LED lit and 'XE' LED lit

Relay coil open cct. XENC indication - open cct.






Fails to switch over when XE applied

XENC1 and XENC2 latching does not register in TSC



By TSC seeing XENC1 high when XENO1 is high By technician observing 'XE fault' LED lit and 'XE' LED lit

Excessive current welds contacts. XENC continuously applied.


3 R3 Relay - TDNO Contact 6 welded Fails to switch over when TD applied

TDNO1 latching does not register in TSC

TSC assumes there is a TD present, but will a log a fault as TDNC does not match.

Train Demand present By TSC seeing TDNO1 low when TDNC1 is low.



3.1 Contact 8 welded Fails to switch over when TD removed



NO Train Demand present

By TSC seeing TDNO1 high when TDNC1 is high By technician observing 'TD fault' LED lit and 'TD' LED lit





None NO Train Demand present

By technician observing 'TD fault' LED lit and 'TD' LED lit



3.3 Contact 11 welded Fails to switch over when TD applied


None Train Demand present By technician observing 'TD fault' LED lit and 'TD' LED lit




Fails to switch over when TD applied

TDNO1 and TDNO2 latching does not register in TSC


Train Demand present By TSC seeing TDNO1 low when TDNC1 is low By technician observing 'TD fault' LED lit and 'TD' LED lit

Relay coil open cct. TDNO indication - open cct.



Fails to switch over when TD removed

TDNO1 and TDNO2 latching does not register in TSC



By TSC seeing TDNO1 high when TDNC1 is high By technician observing 'TD fault' LED lit and 'TD' LED lit

Excessive current welds contacts. TDNO continuously applied.


4 R4 Relay - TDNC Contact 6 welded Fails to switch over when TD removed

TDNC2 latching does not register in TSC

None NO Train Demand present

By technician observing 'TD fault' LED lit and 'TD' LED lit





None Train Demand present By technician observing 'TD fault' LED lit and 'TD' LED lit






Train Demand present By TSC seeing TDNC1 high when TDNO1 is high







By TSC seeing TDNC1 low when TDNO1 is low




Fails to switch over when TD removed

TDNC1 and TDNC2 latching does not register in TSC



By TSC seeing TDNC1 low when TDNO1 is low By technician observing 'TD fault' LED lit and 'TD' LED lit

Relay coil open cct. TDNC indication - open cct.



Fails to switch over when TD applied

TDNC1 and TDNC2 latching does not register in TSC


Train Demand present By TSC seeing TDNC1 high when TDNO1 is high By technician observing 'TD fault' LED lit and 'TD' LED lit

Excessive current welds contacts. TDNC continuously applied.


5 R5 Relay - TLRL Contact 6 welded Fails to switch over when WAIT 1 applied

Fails to provide continuity for TLR indication

Rail Authority has to wait until complete TDRT period has expired before applying XE.

Train Demand present By TSC seeing no TLRF when TLR indication given By technician observing detector inputs and WAIT outputs via HHT


5.1 Contact 8 welded Fails to switch over when WAIT 1 applied



















Fails to switch over when WAIT 1 applied







Fails to break continuity for TLR indication

No effect if TLRH is working correctly NO Train Demand present

None Relay contacts are not Forced-guided contacts, ie one can change while the other does not.

6 R6 Relay - TLRH Contact 6 welded Fails to switch over when WAIT 3 applied




























Fails to break continuity for TLR indication

No effect if TLRL is working correctly NO Train Demand present

None Relay contacts are not Forced-guided contacts, ie one can change while the other does not.

7 R7 Relay - TLRF Contact 6 welded Not used None None None None Relay contacts are not Forced-guided contacts, ie one can change while the other does not.

7.1 Contact 8 welded Not used None None None None Relay contacts are not Forced-guided contacts, ie one can change while the other does not.

7.2 Contact 9 welded TLRF indication provided continuously

None None None By TSC seeing TLRF when no TLR indication given By technician observing detector inputs and WAIT outputs via HHT


7.3 Contact 11 welded TLRF indication never provided

None None None By TSC seeing no TLRF when TLR indication given By technician observing detector inputs and WAIT outputs via HHT






TLRF indication never provided

None None None By TSC seeing no TLRF when TLR indication given By technician observing detector inputs and WAIT outputs via HHT



TLRF indication provided continuously

None None None By TSC seeing TLRF when no TLR indication given By technician observing detector inputs and WAIT outputs via HHT


8 D1 Grn LED Diode - 'Relay Supply'

Open Cct Fails to light when relay power supply is connected

None None None By technician observing 'Relay Supply' LED as unlit and checking that relay supply is actually connected.

8.1 Short Cct Fails to light when relay power supply is connected

None None None By technician observing 'Relay Supply' LED as unlit and checking that relay supply is actually connected.

9 D2 Diode Open Cct Fails to provide back emf path for relay 7 de-energising

None None None None Alternate de-energising route via diode D13 available

9.1 Short Cct TLRFB' LED may fail to light

No indication to the maintainer that TLF indication is being given.

None None By technician observing 'TLRFB' LED unlit. Would also need to observe detector inputs via HHT

10 D3 Grn LED Diode - 'TLRF'

Open Cct Fails to light when TLRF indication from rail authority

None None None By technician observing 'TLRFB' LED unlit. Would also need to observe detector inputs via HHT

10.1 Short Cct Fails to light when TLRF indication from rail authority

None None None By technician observing 'TLRFB' LED unlit. Would also need to observe detector inputs via HHT

11 D4 Diode Open Cct Fails to provide reverse path for 32v AC negative half cycle around ‘XE fault’ LED

Reverse breakdown of ‘XE fault’ LED likely

No visual indication of a XE fault None None

11.1 Short Cct May result in ‘XE fault’ LED not lighting when there is a fault with XE.

Fault in XE not visually indicated to Technician

None Must be a fault in XE None Provides a least resistance path around 'XE fault' LED

12 D5 Red LED Diode - 'XE fault'

Open Cct Fails to light when there is an XE fault


None Must be a fault in XE None

12.1 Short Cct Fails to light when there is an XE fault


None Must be a fault in XE None

13 D6 Grn LED Diode - 'XE'

Open Cct Fails to light when there is an XE indication

XE indication not visually given to the Technician

None Crossing Operating present

By technician observing 'XE' LED unlit when crossing operating or observing detectors via HHT.

13.1 Short Cct Fails to light when there is an XE indication

XE indication not visually given to the Technician



14 D7 Diode Open Cct Fails to provide reverse path for 32v AC negative half cycle around ‘XE’ LED

Reverse breakdown of ‘XE’ LED likely

No visual indication of a XE - crossing operating

None None

14.1 Short Cct May result in ‘XE’ LED not lighting when XE - crossing operating signal is present.

XE - Crossing operating not visually indicated to Technician



Provides a least resistance path around 'XE' LED




15 D8 Diode Open Cct Fails to provide reverse path for 32v AC negative half cycle around ‘TD fault’ LED

Reverse breakdown of ‘TD fault’ LED likely

No visual indication of a TD fault None None

15.1 Short Cct May result in ‘TD fault’ LED not lighting when there is a fault with TD.

Fault in TD not visually indicated to Technician

None Must be a fault in TD None Provides a least resistance path around 'TD fault' LED

16 D9 Red LED Diode - 'TD fault'

Open Cct Fails to light when there is an TD fault


None Must be a fault in TD None

16.1 Short Cct Fails to light when there is an TD fault


None Must be a fault in TD None

17 D10 Grn LED Diode - 'TD'

Open Cct Fails to light when there is an TD indication

TD indication not visually given to the Technician

None Train Demand present By technician observing 'TD' LED unlit and observing detectors via HHT.

17.1 Short Cct Fails to light when there is an TD indication

TD indication not visually given to the Technician


18 D11 Diode Open Cct Fails to provide reverse path for 32v AC negative half cycle around ‘TD’ LED

Reverse breakdown of ‘TD’ LED likely

No visual indication of a TD - Train demand

None None

18.1 Short Cct May result in ‘TD’ LED not lighting when TD - Train demand signal is present.

TD - Train demand not visually indicated to Technician


Provides a least resistance path around 'TD' LED

19 D12 Grn LED Diode - '30v AC'

Open Cct Fails to light when detector supply is connected

None None None By technician observing '30v AC' LED as unlit and checking that detector supply is actually connected.

19.1 Short Cct Fails to light when detector supply is connected

None None None By technician observing '30v AC' LED as unlit and checking that detector supply is actually connected.

20 D13 Diode Open Cct Fails to provide alternate back emf path for relays 1, 2, 3, 4 and 7 de-energising

None None None None Main de-energising route available for relays 1, 2, 3, 4 and 7

20.1 Short Cct Relay Supply' LED may fail to light

No indication to the maintainer that Relay Supply is connected being given.

None None By technician observing 'Relay Supply' LED as unlit and checking that relay supply is actually connected.

21 D14 Diode Open Cct Loss of TLRH circuit continuity

TLRH relay cannot be activated

No TLR indication to rail authority, TDRT maximum always used.


21.1 Short Cct Relay TLRH can be operated by COUT2 going low.

Incorrect TLRH activation

None if TLRL operating correctly COUT2 must be driven low incorrectly

None


High voltage spike occurs

Possible arcing and damage to TSC WAIT output components

Removal of TLR None

22.1 Short Cct Loss of TLRL circuit continuity

TLRL relay cannot be activated








Possible arcing and damage to TSC WAIT output components

Removal of TLR None

23.1 Short Cct Loss of TLRH circuit continuity

TLRH relay cannot be activated



24 D17 Diode Open Cct Fails to provide reverse path for 32v AC negative half cycle around ‘30v AC’ LED

None None None None

24.1 Short Cct May result in ‘30v AC’ LED not lighting when detector supply connected.

No indication to the maintainer that 32v AC supply is connected being given.

None None By technician observing '30v AC' LED as unlit and checking that 32v AC supply is actually connected.

25 R1 Resistor 1 Open Cct Causes current in XENO circuit to drop from 42mA to ≈ 17mA

None None - minimum wetting current for Rail Authority relay contacts is 10mA.

None None

25.1 Fails to provide back emf path for relay 1 de-energising


Possible arcing and damage to Rail Authority components

Removal of XE None

25.2 Short Cct Causes current in XENO circuit to climb from 42mA to unacceptable levels

Relay 1 by passed. Therefore not energised when XE present

High current may cause Rail Authority relay contacts to become welded causing XENO to become permanently closed.

Crossing Operating present

By TSC seeing XENO1 high when XENC1 is also high

25.3 NO Crossing Operating present

By TSC seeing XENO1 high when XENC1 is also high By technician observing 'XE fault' LED lit and 'XE' LED lit

25.4 Drift ± 50% None None None None None

26 R2 Resistor 2 Open Cct Causes current in XENC circuit to drop from 42mA to ≈ 17mA


None None




Application of XE None

26.2 Short Cct Causes current in XENC circuit to climb from 42mA to unacceptable levels

XENC1 - permanently high

High current may cause Rail Authority relay contacts to become welded causing XENC to become permanently closed.

Crossing Operating present

By TSC seeing XENC1 high when XENO1 is also high By technician observing 'XE fault' LED lit and 'XE' LED lit when there is no train demand

26.3 NO Crossing Operating present

By TSC seeing XENC1 high when XENO1 is also high


27 R3 Resistor 3 Open Cct Causes current in TDNC circuit to drop from 42mA to ≈ 17mA


None None




Removal of TD None




27.2 Short Cct Causes current in TDNC circuit to climb from 42mA to unacceptable levels

TDNO1 - permanently high

High current may cause Rail Authority relay contacts to become welded causing TDNO to become permanently closed.

Train Demand present By TSC seeing TDNO1 high when TDNC1 is also high

27.3 NO Train Demand present

By TSC seeing TDNO1 high when TDNC1 is also high By technician observing 'TD fault' LED lit and 'TD' LED lit


28 R4 Resistor 4 Open Cct Causes current in TDNC circuit to drop from 42mA to ≈ 17mA


None None




Application of TD None

28.2 Short Cct Causes current in TDNC circuit to climb from 42mA to unacceptable levels

TDNC1 - permanently high

High current may cause Rail Authority relay contacts to become welded causing TDNC to become permanently closed.

Train Demand present By TSC seeing TDNC1 high when TDNO1 is also high By technician observing 'TD fault' LED lit and 'TD' LED lit when there is no train demand

28.3 NO Train Demand present

By TSC seeing TDNC1 high when TDNO1 is also high


29 R5 Resistor 5 Open Cct Voltage supply to 'Relay Supply' LED halted.

None None Power connected By technician observing 'Relay Supply' LED unlit.

29.1 Short Cct Voltage through 'Relay Supply' LED rises to the extent that 'Relay Supply' LED is blown

None None Power connected By technician observing 'Relay Supply' LED unlit.

29.2 Drift 50% original Current rises to ≈ 30mA Relay Supply' LED intensity rises to 100%

None None None

29.3 Drift twice original Current falls to ≈ 8mA Relay Supply' LED intensity falls ≈ 50%

None None None

30 R6 Resistor 6 Open Cct Voltage supply to 'TLRFB' LED halted.

None None TLR is present By technician observing 'TLRFB' LED unlit. Would also need to observe detector inputs via HHT




Removal of TLR None

30.2 Short Cct Voltage through 'TLRFB' LED rises to the extent that 'TLRFB' LED is blown

TLRFB' LED fails to light None TLR is present By technician observing 'TLRFB' LED unlit. Would also need to observe WAIT outputs and detector inputs via HHT

30.3 Would allow less resistive path and therefore bypass TLRF relay (RL7)

TLR feedback relay would not energise. No feedback to TSC of TLR being received

None TLR is present By technician observing 'TLRFB' LED unlit. Would also need to observe WAIT outputs and detector inputs via HHT

30.4 Drift 50% original Current rises to ≈ 30mA Relay Supply' LED intensity rises to ≈ 125%

None None None

30.5 Drift twice original Current falls to ≈ 8mA Relay Supply' LED intensity falls ≈ 50%

None None None




31 R8 Resistor 8 Open Cct Voltage supply to 'XE fault' LED halted.

Fault diagnosis lost None Crossing Operating present & fault with XE signal

By technician observing 'XE fault' LED unlit. Would also need to observe detector inputs via HHT

31.1 Short Cct Voltage through 'XE fault' LED rises to the extent that 'XE fault' LED is blown and possible welding of relay 1 & relay 2 (XENO & XENC) contacts

Fault diagnosis lost None Crossing Operating present & fault with XE signal

By technician observing 'XE fault' LED unlit. Would also need to observe detector inputs via HHT

31.2 Drift 50% original Current rises to ≈ 27mA XE Fault' LED intensity rises to ≈ 125%

None None None

31.3 Drift twice original Current falls to ≈ 7mA XE Fault' LED intensity falls ≈ 40%

None None None

32 R9 Resistor 9 Open Cct Voltage supply to 'XE' LED halted.

Fault diagnosis lost None Crossing Operating present

By technician observing 'XE' LED unlit.

32.1 Short Cct Voltage through 'XE' LED rises to the extent that 'XE' LED is blown and possible welding of relay 1 & relay 2 (XENO & XENC) contacts

Fault diagnosis lost None Crossing Operating present

By technician observing 'XE' LED unlit.

32.2 Drift 50% original Current rises to ≈ 26mA XE' LED intensity rises to ≈ 110%

None None None

32.3 Drift twice original Current falls to ≈ 6mA XE' LED intensity falls ≈ 40%

None None None

33 R10 Resistor 10 Open Cct Voltage supply to 'TD' LED halted.

Fault diagnosis lost None Train Demand present By technician observing 'TD' LED unlit.

33.1 Short Cct Voltage through 'TD' LED rises to the extent that 'TD' LED is blown and possible welding of relay 3 & relay 4 (TDNO & TDNC) contacts

Fault diagnosis lost None Train Demand present By technician observing 'TD' LED unlit.

33.2 Drift 50% original Current rises to ≈ 26mA TD' LED intensity rises to ≈ 110%

None None None

33.3 Drift twice original Current falls to ≈ 6mA TD' LED intensity falls ≈ 40%

None None None

34 R11 Resistor 11 Open Cct Voltage supply to '30v AC' LED halted.

None None Power connected Train Demand present

By technician observing '30v AC' LED unlit while 'TD' lit.

34.1 Short Cct Voltage through '30v AC' LED rises to the extent that '30v AC' LED is blown

None None Power connected Train Demand present

By technician observing '30v AC' LED unlit while 'TD' lit.

34.2 Drift 50% original Current rises to ≈ 26mA 30v AC' LED intensity rises to ≈ 110%

None None None

34.3 Drift twice original Current falls to ≈ 6mA 30v AC' LED intensity falls ≈ 40%

None None None

35 R12 Resistor 12 Open Cct Voltage supply to 'TD fault' LED halted.

Fault diagnosis lost None Train Demand present & fault with TD signal

By technician observing 'TD fault' LED unlit. Would also need to observe detector inputs via HHT




35.1 Short Cct Voltage through 'TD fault' LED rises to the extent that 'TD fault' LED is blown and possible welding of relay 3 & relay 4 (TDNO & TDNC) contacts

Fault diagnosis lost None Train Demand present & fault with TD signal

By technician observing 'TD fault' LED unlit. Would also need to observe detector inputs via HHT

35.2 Drift 50% original Current rises to ≈ 27mA TD Fault' LED intensity rises to ≈ 125%

None None None

35.3 Drift twice original Current falls to ≈ 7mA TD Fault' LED intensity falls ≈ 40%

None None None

36 R13 Resistor 13 Open Cct No voltage supply to TLRL

TLR indication not given to Rail authority

TDRT maximum always used. TLR indication required to be given

By TSC seeing no TLRF when TLR indication given By technician observing detector inputs and WAIT outputs via HHT

36.1 Short Cct Voltage through TLRL would rise significantly

None None TLR indication required to be given

None Currently specified relays (MT2C93418) can handle 24v adequately

36.2 Drift 50% original Voltage drop across relay 5 increases significantly.



36.3 Drift twice original Voltage drop across relay 5 decreases significantly.


None Currently specified relays (MT2C93418) can operate down to 7.8v (which would equate to a resistor drift of over 3 times original).

37 R14 Resistor 14 Open Cct No voltage supply to TLRH




37.1 Short Cct Voltage through TLRH would rise marginally


None

37.2 Drift 50% original Voltage drop across relay 6 increases.


None

37.3 Drift twice original Voltage drop across relay 6 decreases.


None

37.4 Short Cct Shorts the TSC 12 v dc supply to the TSC WAIT outputs

May cause a problem for the TSC having the 12 v dc supply short to the active low TSC WAIT outputs

TLR indication is falsely being given (COUT1 and COUT3 are active low) & is required to be suppressed (COUT2 is active low)

37.5 Drift 50% original Marginal increase in current through circuit

None None None None

37.6 Drift twice original Marginal decrease in current through circuit

None None None None

38 R15 Resistor 15 Open Cct No voltage supply to TLRH







38.1 Short Cct Voltage through TLRL would rise significantly



38.2 Drift 50% original Voltage drop across relay 6 increases significantly.



38.3 Drift twice original Voltage drop across relay 6 decreases significantly.


None Currently specified relays (MT2C93418) can operate down to 7.8v (which would equate to a resistor drift of over 3 times original).

39 R16 Resistor 16 Open Cct TLR indication lost TLR indication not given to Rail authority



39.1 Short Cct Current would increase marginally over 'normal' operation in TLR circuit


None

39.2 Drift 50% original Current would increase marginally over 'normal' operation in TLR circuit


None

39.3 Drift twice original Current would decrease marginally over 'normal' operation in TLR circuit


None

40 R17 Resistor 17 Open Cct TLR indication lost TLR indication not given to Rail authority



40.1 Short Cct Current would increase marginally over 'normal' operation in TLR circuit


None

40.2 Drift 50% original Current would increase marginally over 'normal' operation in TLR circuit


None

40.3 Drift twice original Current would decrease marginally over 'normal' operation in TLR circuit


None

41 R220 Resistor Open Cct Fails to provide back emf path for Rail Authority's TLR relay de-energising


Possible arcing and damage to TLRL and TLRH contacts

TLR indication required to be given

None

41.1 Short Cct Significant Increase in current on initial circuit activation (falls as capacitor charges). No affect once capacitor has fully charged.

Resistors 16 and 17 may act like a fuse.

None TLR indication required to be given

None

41.2 Drift 50% original Current would increase over 'normal' operation in TLR circuit by ≈ 50%

Decrease in time for Capacitor to charge


None

41.3 Drift twice original Current would decrease over 'normal' operation in TLR circuit by ≈ 25%

Increase in time for Capacitor to charge


None




42 C1 Capacitor Open Cct Fails to provide back emf path for Rail Authority's TLR relay de-energising




None

42.1 Short Cct Fails to provide back emf path for Rail Authority's TLR relay de-energising




None

42.2 Would allow less resistive path and therefore bypass Rail Authority components




42.3 Resistor R220 is an active component continuously

Higher current through the circuit for longer

None None None

42.4 Drift 50% original ≈ 50% decrease in time for Capacitor to charge


None

42.5 Drift twice original ≈ 100% increase in time for Capacitor to charge


None


For further enquirieswww.rta.nsw.gov.au13 22 13

July 2009

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